A flexible arm is used for flexibly changing the orientation of a device. For example, Japanese Patent Application Publication No. 8-56946 (JP 8-56946 A) discloses a freely bendable flexible arm (coil shaft). In this document, it is disclosed that, in this flexible arm, a clearance is provided in advance between adjacent wire rods of a coil that constitutes the flexible arm such that the adjacent wire rods contact each other in a state where the flexible arm is bent with a maximum degree expected in actual use.